Toad Battery Charger

[Geobiker]

We have a 2012 Honda CRV which we tow behind a 2004 Jayco Granite Ridge MH. Prior to a long trip we had asked to have a charge line installed between the MH and Honda as well as a toad charger. At the end of day 2 the Honda battery is dead. When we took it to another technician, the charge line is in and working but no toad charger.

So, what toad charger are you using, do you like it and why? We have another cross country trip planned and do not want a dead Honda battery.

Thanks and safe travels.

[Geobiker]

Pianotuna, time2roll and willald, thanks for responding; good ideas.

[Geobiker]

Krusty, we have a 10 gauge charge line; I think the ground wire is the same but will double check.

[Krusty]

What gauge is your charge wire? I would use at least 10 gauge. Is there an equally sized ground wire grounding the two vehicles together as well?

[pianotuna]

#8 or #10 wire.

Add a dc to DC charger.

Measure the draw on the Honda battery when it is stand alone.

In your shoes I'd move to an SiO2 battery for the Honda.

[willald]

Geobiker wrote:
...None the less when towing between LA and Albuquerque at the end of day 2 (Albuquerque) the Honda batters is completely dead.

Just saw this where you said day 2, and it made me wonder about one other possibility:

Are you traveling for 2 days, maybe boondocking one night or stopping for a few hours at one point, and leaving the Honda hitched up to MH during that time? Do you have to leave the Honda ignition in ON or ACC while towing?

If that is the case, you may have a situation like I had on the Ford Taurus and Ford Fusion hybrid I used to tow: When towing, the towed vehicle's ignition had to stay on, in ACC position. This would drain the battery over course of a few hours, which is why I had to install a charge line when towing.

Any time we stopped for more than an hour or so, I'd have to go in the towed vehicle and shut the ignition off and put it in park to keep battery from draining. Then, before we'd hit the road, turn ignition back on and shift tranny back into neutral.

If I didn't do that, battery would run down after a while even with a charge line. That is because when MH ignition shuts off, in most cases after a short time, power to that charge line will shut off and no more charge going to your towed vehicle.

Anyway, just thought I'd mention this as one other possibility.

[willald]

time2roll wrote:
Testing voltage is great.... however next shop have them measure the amps. Need to load the Honda battery with the lights or something. Should see 10+ amps flowing from the RV to the car. Even 1 amp into a charged battery will show full voltage. If the shop does not have a clamp-on ammeter they need to get one or find a new shop.

Then put in towing mode and see what load is actually on the car battery to power the brakes etc.

This is an excellent point I hadn't thought about.

What gauge of wire are you using for the charge line and the ground wire going between MH and the towed? Both would need to be at least 14 or 16 gauge, I'd think, to allow sufficient amperage to keep the battery charged. Also, what amperage is the fuse you have on the charge line?

Maybe this is a case where you are taking power (amps) away from the Honda's battery faster than charge line from MH can replace it.

[time2roll]

Testing voltage is great.... however next shop have them measure the amps. Need to load the Honda battery with the lights or something. Should see 10+ amps flowing from the RV to the car. Even 1 amp into a charged battery will show full voltage. If the shop does not have a clamp-on ammeter they need to get one or find a new shop.

Then put in towing mode and see what load is actually on the car battery to power the brakes etc.

[Geobiker]

Thanks to all who responded to my original post of 1/25.

Yesterday, I met with my technician. He tested the entire system from the battery in the motorhome to the battery in the Honda CRV, including fuses. All tested 100% ok. Voltages were 13+. He inspected the entire charge line for damage/problems; again all ok. We could find nothing either installed incorrectly or working incorrectly that would cause the Honda battery to go dead.

None the less when towing between LA and Albuquerque at the end of day 2 (Albuquerque) the Honda batters is completely dead.

I have had 2 different technicians try to solve my problem but the bottom line is the charge line I have should keep the Honda battery charged while towing.

I am totally frustrated. Help!!! I welcome any further ideas.

[camperdave]

FWIW, the RVI toad charger is nothing special, imo. You are basically paying for the ability to monitor your toad battery from the proprietary RVI hub and tablet.

It seems to actually have more of a voltage drop than a simple fuse/diode would.

I use the RVI because it came with the brake system I bought used. I certainly wouldn't pay $120 (I don't actually know how much it is, since they don't show a price until you log, which is a bit sus).

I agree with Willald, put a voltmeter on the TOAD battery with and without the motorhome running. What's it read? Any chance you just need to replace a fuse in the charge line (should be very close to the TOAD battery itself)?

[willald]

Are you certain that the charge line is in and working? Meaning, have you verified with a voltmeter that when Motorhome engine is running, there is 13 volts on the charge line going to your Honda's battery?

I have flat towed a total of 4 different vehicles over last 10 years. Two of them would have a dead battery after just a few hours of towing. I installed a charge line and used such with all of them, and that was always enough to keep the battery fully charged no matter how long we towed. No charger was ever necessary, just a simple 14 gauge wire going from the + terminal of Motorhome battery, over to + terminal of towed vehicle (with an inline fuse or breaker).

Before spending the time and $$ to install a DC charger, I'd make certain the charge line you have running to the Honda actually has power. If it does, then that charge line should be enough to keep your battery charged up, without having to add a charger.

[pianotuna]

Geobiker,

Look into dc to DC chargers. Mine is from Renogy

https://www.renogy.com/12v-20a-dc-to-dc-on-board-battery-charger/?gclid=Cj0KCQiAw8OeBhCeARIsAGxWtUza...

[Y-Guy]

I haven't bought it but I was reading about the RVi Towed Battery Charger Plus for Flat Towing